Transcript of "Online Search Techniques-Boolean Searching"

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BOOLEAN SEARCHING• Also called “Boolean Logic.”• A type of search syntax or search technique which helps the user conduct a better, more exact search.• It is used when searching using more than one keyword or phrase.• When conducting a search, a person uses the Boolean operators: AND, OR, and NOT.• These operators are used to link words and phrases for more precise queries.

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WHERE DOES BOOLEAN COME FROM?• Boolean logic takes its name from British mathematician George Boole (1815-1864), who wrote about a system of logic designed to produce better search results by formulating precise queries.• He called it the "calculus of thought."• From his writings, we have derived Boolean logic and its operators: AND, OR, and NOT.

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HOW BOOLEAN LOGIC WORKS• It uses the words AND, OR and NOT to search for items containing both terms, either term, or a term only if not accompanied by another term.• All databases and web search engines have help pages explaining how Boolean logic works in their specific system.

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BOOLEAN “AND”• The Boolean AND actually narrows your search by retrieving only documents that contain every one of the keywords you enter. The more terms you enter, the narrower your search becomes. EXAMPLE: truth AND justice EXAMPLE: truth AND justice AND ethics AND congress

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BOOLEAN “OR”• The Boolean OR expands your search by returning documents in which either or both keywords appear. Since the OR operator is usually used for keywords that are similar or synonymous, the more keywords you enter, the more documents you will retrieve. EXAMPLE: college OR university EXAMPLE: college OR university OR institution OR campus

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BOOLEAN “OR”• A search for „rock OR roll‟ will locate all records containing either the word “rock” or the word “roll” – not necessaril both. (same as „any‟)

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BOOLEAN “NOT” / “AND NOT”• The Boolean NOT or AND NOT (sometimes typed as ANDNOT) limits your search by returning only your first keyword but not the second, even if the first word appears in that document, too. EXAMPLE: saturn AND NOT car EXAMPLE: pepsi AND NOT coke• Tip: NOT can be dangerous. Lets say you want to search for items about Mexico, but not New Mexico, so you use NOT to exclude the word "New" from your retrieved set. This would prevent you from retrieving an article about "New regulations in Mexico" because it contained the word "New," although that wasnt what you intended.

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BOOLEAN “NOT” / “AND NOT”• A search for „rock NOT roll‟ will locate records containing the word “rock” but NOT the word “roll.”

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BOOLEAN LOGIC A search for ‘rock AND roll’ will locate all records containing both the word "rock" and the word "roll.” (same as ‘all’) A search for ‘rock OR roll’ will locate all records containing either the word "rock" or the word "roll" -- not necessarily both. (same as ‘any’)A search for ‘rock NOT roll’will locate recordscontaining the word "rock"but NOT the word "roll”.

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NESTING . . . WITH BOOLEAN OPERATORS• Nesting, i.e., using parentheses, is an effective way to combine several search statements into one search statement. Use parentheses to separate keywords when you are using more than one operator and three or more keywords. EXAMPLE: (hybrid OR electric) AND (Toyota OR Honda)• For best results, always enclose OR statements in parentheses.

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IMPLIED BOOLEAN OPERATORS• Implied Boolean operators use the plus (+) and minus (-) symbols in place of the full Boolean operators, AND and NOT. Typing a (+) or (-) sign in front of a word will force the inclusion or exclusion of that word in the search statement. EXAMPLE: +dementia -alzheimers• Similarly, putting double quotation marks (" ") around two or more words will force them to be searched as a phrase in that exact order. EXAMPLE: "green tea” • In some databases and search engines, you may have to select “Exact phrase.”

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THINGS TO CONSIDER WHEN USING BOOLEAN LOGIC• Different databases and search engines handle Boolean operators differently. For example, some accept NOT, while one accepts ANDNOT as one word, others AND NOT as two words. Some require the operators to be typed in capital letters while others do not.• You may have to indicate if it‟s a Boolean search. This option would usually be available in the advanced search option.• Different databases and search engines may only allow full Boolean operators in the advanced search option, while implied Boolean operators may only be used in the basic search options or vice versa.

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THINGS TO CONSIDER WHEN USING BOOLEAN LOGIC• Some databases and search engines use drop- down menu options to spell out the Boolean logic in short phrases.• For example . . . • "All of the words" or "Must contain” = AND • "Any of the words" or "Should contain” = OR • "Must not contain” = NOT.

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ACTIVITIES• Using Google‟s advanced search page, use different Boolean operators to search for the words truth and justice.